Duct

ABSTRACT

A duct including a duct body is disclosed. The duct is a hollow tube and includes an air channel and an exit end. The exit end has a windward portion and an air-guiding portion on two sides thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a duct of a smokestack and,more particularly, to a duct of a smokestack that provides faster heatexpelling by increasing air pressure difference between interior air andexterior air.

2. Description of the Related Art

Smokestacks are commonly seen in a variety of buildings and factories. Asmokestack has a duct and can create a difference in air pressurebetween interior air and exterior air. Heat (or waste gas) in the ductwill rise, and the air pressure difference can facilitate expelling theheat in the duct while drawing clean air from the outside at the sametime. When the heat gets to an exit of the smokestack, the wind willblow away the expelled heat, thereby attaining ventilation and coolingeffects of the smokestack.

Referring to FIG. 1, a conventional duct 9 has an air channel 91 and anexit 92. The duct 9 can be used to construct a smokestack for someequipment such as a furnace or the like. The smokestack has an entry andan exit, and there is a big difference in air pressure between the entryand the exit. During operation of the furnace, a significant amount ofheat will be generated, and the heat will rise in the air channel 91 ofthe duct 9. At this point, the air pressure difference will push theheat out of the duct 9. When the rising heat gets to the exit 92 of theduct 9, an air-pulling effect created by the wind blowing over thesmokestack will blow away the heat. In such a manner, desiredventilation can be provided to improve burning of the furnace.

Since the exit 92 of the duct 9 has an even periphery, however, the windtends to interact with the expelled heat at the exit 92. The interactionbetween the wind and the expelled heat will slow down the heat in theduct 9. As a result, heat emission and cooling efficiency of the duct 9are impacted. In light of this problem, it is desired to improve theduct 9.

SUMMARY OF THE INVENTION

It is therefore the primary objective of this invention to provide aduct capable of increasing the air pressure difference between interiorair and exterior air to better create an air-pulling effect at an exitof the duct.

It is another objective of this invention to provide a duct capable ofautomatically adjusting the direction thereof based on wind direction,thus maintaining the air-pulling effect at the exit of the duct.

The invention discloses a duct including a duct body. The duct is ahollow tube and includes an air channel and an exit end. The exit endhas a windward portion and an air-guiding portion on two sides thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinafter and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a cross-sectional view of a conventional duct.

FIG. 2 is a cross-sectional view of a duct according to a firstembodiment of the invention.

FIG. 3 is an exploded view of a duct according to a second embodiment ofthe invention.

FIG. 4 is a cross-sectional view of the duct of the second embodiment ofthe invention.

FIG. 5 is a top view of a first tube of the duct rotating upon a slidingmember according to the second embodiment of the invention.

FIG. 6 is a top view of the first tube of the duct resting on thesliding member according to the second embodiment of the invention.

FIG. 7 is an exploded view of a duct according to a third embodiment ofthe invention.

In the various figures of the drawings, the same numerals designate thesame or similar parts. Furthermore, when the term “first”, “second”,“third”, “fourth”, “inner”, “outer” “top”, “bottom” and similar termsare used hereinafter, it should be understood that these terms referonly to the structure shown in the drawings as it would appear to aperson viewing the drawings, and are utilized only to facilitatedescribing the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, a duct including a duct body 1 is disclosedaccording to a first embodiment of the invention. The duct body 1 is ahollow tube and has an air channel 11 that allows air to passtherethrough. The duct body 1 has an exit end 12 on one end thereof, andthe exit end 12 may form a windward portion 13 and an air-guidingportion 14. In this embodiment, the exit end 12 forms a cut-off portionwith an uneven periphery. Namely, a portion of circumferential wall ofthe duct body 1 is cut off at the exit end 12 to form the cut-offportion. Specifically, the windward portion 13 has two ends 131 and 132,and the two ends 131 and 132 may jointly define the air-guiding portion14. The two ends 131 and 132 of the windward portion 13 may be parallelto a vertical direction of the duct as shown in FIG. 3, but is notlimited thereto.

Referring to FIG. 2, when the duct is in use, the duct should bedisposed according to wind direction. Specifically, the windward portion13 of the duct body 1 should face the wind such that a high air pressurearea A can be defined on a surface of the windward portion 13. When thestrong wind of the high air pressure area A blows over the cut-offportion of the exit 12, the wind will be instantaneously speeded up dueto the gradient in air pressure, creating a low air pressure area B onthe air-guiding portion 14. At the instant, the air pressure differencebetween the high air pressure area A and the low air pressure area Bwill result in boundary layer separation of the airflows on theair-guiding portion 14. Therefore, eddy occurs. At the same moment,there results in a difference in air pressure between interior air andexterior air of the duct body 1, creating an air-pulling effect thatpulls up the air from the air channel 11.

Referring to FIG. 2, the duct body 1 preferably comprises a narrowportion 15 which can speed up the heat passing therethrough. This causesa local low air pressure that facilitates expelling the heat of the ductbody 1 and therefore provides improved air circulation.

Referring to FIGS. 3 and 4, a duct is disclosed according to a secondembodiment of the invention. The duct body 1 also has the exit end 12,windward portion 13, air-guiding portion 14 and narrow portion 15described in the first embodiment. The duct of the second embodimentdiffers from that of the first embodiment in that the duct body 1consists of a first tube 1 a and a second tube 1 b. The first tube 1 ahas a first air channel 11 a and the second tube 1 b has a second airchannel 11 b. The exit end 12, windward portion 13, air-guiding portion14 and narrow portion 15 are formed on one end of the first tube 1 a.

The first tube 1 a and the second tube 1 b are coupled together invarious conventional ways. As shown in FIG. 3, the first tube 1 a andthe second tube 1 b are coupled together via a sliding member 16. Inthis embodiment, the first tube 1 a further comprises a first couplingmember 17 a abutting against one face of the sliding member 16, with theother face of the sliding member 16 coupled with a coupling seat 17 b ofthe second tube 1 b. In such a manner, the sliding member 16 can supportthe first tube 1 a and allow the first tube 1 a to rotate about thesecond tube 1 b. The sliding member 16 may be a ball bearing, a needlebearing, a sliding bearing, a magnetic suspension bearing, a hydraulicbearing, a tapered and cylindrical roller bearing or any similarstructures that can support the first tube la and provide rotationtherefor. In this embodiment, the sliding member 16 is implemented asthe tapered and cylindrical roller bearing.

The first tube 1 a may further comprise a pair of wings 18 capable ofgenerating a torque when the direction of the wind changes. The wings 18are shown to be arranged on the first tube 1 a for illustration purpose.Specifically, the wings 18 are aligned with each other in a radialdirection of the duct while located at two opposing positions on anouter circumferential face of the first tube 1 a. Further, the wings 18are preferably located on two ends of the windward portion 13 andaligned with the cut-off portion of the exit end 12. Specifically, thewings 18 are aligned with the cut-off portion in such a way that thewings 18 are aligned with the two ends 131 and 132 of the windwardportion 13 in the vertical direction. In addition, the wings 18 arepreferably not higher than the cut-off portion of the exit end 12 inorder not to disturb the eddy system at the exit end 12.

Referring to FIGS. 5 and 6, operation diagrams of the wings 18 and thesliding member 16 are shown. The wings 18 can define a central referenceline X having two ends. The two ends of the central reference line X mayexperience different wind strength. For example, referring to FIG. 5,one end of the central reference line X may experience larger windstrength than the other one. In this case, the wings 18 will be drivenby the wind and therefore cause the first tube 1 a to rotate via thesliding member 16 until the two ends of the central reference line Xexperience the same wind strength. By the time the first tube 1 a stopsrotating, the windward portion 13 of the first tube 1 a will face thewind, allowing eddies to be generated at the exit end 12 of the firsttube 1 a. The eddies will help blow away the expelled heat of the duct.In such an arrangement, the duct in the second embodiment canautomatically adjust the direction of the windward portion 13 based onwind direction, thereby providing faster heat emission.

Referring to FIG. 7, a duct is disclosed according to a third embodimentof the invention. In the third embodiment, the duct also has the firsttube 1 a, second tube 1 b and narrow portion 15 described above. Theduct of the third embodiment differs from those of the first and secondembodiments in that the exit end 12 has an inclined periphery. Similarto the first and second embodiments, the duct in this embodiment alsohas the windward portion 13 and the air-guiding portion 14. Thus, itwill be more convenient to manufacture the first tube 1 a.

The duct of the invention can be installed on a roof of a building toexpel dirty air of the building. Further, the duct of the invention canalso construct a part of a smokestack for a conventional furnace or thelike. In generally, the furnace will generate a significant amount ofheat during the burning process thereof. Since the heat has a smallerdensity, the heat will rise in the duct. At this point, the air-guidingportion 14 can increase the speed of airflows, creating a low airpressure area B and resulting in an air pressure difference betweeninterior air and exterior air of the duct. Thus, the heat at the exit 12will be blown away quickly by wind while external clean air is drawninto the duct via the bottom end of the duct, thereby providing improvedburning of the furnace.

Although the invention has been described in detail with reference toits presently preferable embodiment, it will be understood by one ofordinary skill in the art that various modifications can be made withoutdeparting from the spirit and the scope of the invention, as set forthin the appended claims.

1. A duct comprising a duct body being a hollow tube, wherein the ductcomprises an air channel and an exit end, and the exit end has awindward portion and an air-guiding portion on two sides thereof.
 2. Theduct as claimed in claim 1, wherein the duct body further comprises anarrow portion.
 3. The duct as claimed in claim 1, wherein the duct bodyfurther comprises a first tube and a second tube coupled with the firsttube via a sliding member.
 4. The duct as claimed in claim 3, whereinthe sliding member is a ball bearing, a needle bearing, a slidingbearing, a magnetic suspension bearing, a hydraulic bearing or a taperedand cylindrical roller bearing.
 5. The duct as claimed in claim 3,wherein the first tube further comprises a pair of wings.
 6. The duct asclaimed in claim 5, wherein the wings are aligned with the exit end. 7.The duct as claimed in claim 1, wherein the exit end is formed as acut-off portion.
 8. The duct as claimed in claim 1, wherein the exit endhas an inclined periphery.